Army Staff Sgt. Robert Bales, 39, is accused of killing 16 Afghan civilians during a March 11, 2012, rampage. (Spc. Ryan Hallock / Army via AP)

JOINT BASE LEWIS-MCCHORD, WASH. — The U.S. soldier accused of murdering 16 Afghan villagers during a pre-dawn rampage last year appeared in a military courtroom Tuesday for a hearing that focused largely on what might happen if he’s convicted, including which family members and friends could speak on his behalf.

Prosecutors and defense attorneys argued over who might testify in support of Robert Bales at any sentencing hearing, should it come to that. Such testimony could help determine whether he receives the death penalty.

The Ohio native and father of two from Lake Tapps, Washington state, is accused of murdering Afghan villagers, mostly women and children, early on March 11, 2012. Bales, who was on his fourth combat deployment, slipped away from his base in southern Afghanistan to attack two nearby villages and returned soaked in blood, prosecutors say.

He has not yet entered a plea, but it is standard under military law for pretrial motions to address sentencing issues.

Bales’ court martial has been set for September. His lawyers maintain that they cannot be ready to try a death penalty case by then. One of them, Emma Scanlan, is due to give birth that month.

Defense attorneys previously gave the court a list of witnesses they intend to call at sentencing — people who might show their client in a good light or explain anything troubling in his background that might warrant leniency.

Army prosecutors told the judge that not all of the witnesses were necessary. In some cases, the judge, Col. Col. Jeffery Nance, agreed: It likely would be redundant for two of Bales’ older brothers to testify, he said, and so defense attorneys should call just one.

Likewise, the judge said, the defense would not need to call a teacher, principal and football coach from Norwood High School in Norwood, Ohio, where Bales grew up. Two of the three would do, he said.

But Nance did say Bales’ mother and aunt both would be allowed to speak, as they offered differing perspectives on his life. Such testimony from the aunt could include family mental health issues or descriptions of Bales’ mother’s use of alcohol while she was pregnant with him, the judge suggested.

“A lot of our witnesses that we want to testify in a potential penalty phase will be here, including Sgt. Bales’ mother,” Scanlan said after the hearing. “She’s a very important witness to who he was as a child and who he is a man.”

Among the other witnesses defense lawyers might call on Bales’ behalf is his high school football teammate Marc Edwards, a future running back at Notre Dame and later National Football League teams including the 2002 Super Bowl champion New England Patriots.

Other issues discussed at the hearing included the defense team’s request to have a new psychiatric expert to help determine whether Bales was suffering from mental issues, such as post-traumatic stress disorder.

Citing attorney-client privilege, Scanlan did not say why the request was made. The defense team provided its reasons to the judge — but not prosecutors — in a confidential court filing.

Prosecutors objected to the motion, saying it smacked of witness shopping, and the judge said he would rule later. He said the same about the defense team’s request for a consultant to be appointed to help them pick jurors.

During a preliminary hearing late last year, prosecutors built a strong eyewitness case against the veteran soldier, with troops recounting how they saw Bales return to the base alone, covered in blood.